During a vSAN cluster reboot process for a vCenter on vSAN 7.0 U3 scenario, when the orchestration host is powered on, it will initiate the HostStartUpPrecheck task.
This task will check all hosts for their connectivity status periodically. If all hosts are connected, the vSAN cluster power on process will be invoked and executed. Otherwise, the pre-check task monitors several rounds and eventually times out and exits with an error.
When the HostStartUpPrecheck task fails with an error, even though all hosts in the same vSAN cluster are connected again, the vSAN cluster power on process will not be triggered automatically.
This article describes how the HostStartUpPrecheck task can be triggered manually, to invoke the vSAN cluster power on process.